1 /* closeout.c - close standard output 2 3 Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004 Free Software 4 Foundation, Inc. 5 6 This program is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program; if not, write to the Free Software Foundation, 18 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 19 20 #ifdef HAVE_CONFIG_H 21 # include <config.h> 22 #endif 23 24 #include "closeout.h" 25 26 #include <stdio.h> 27 #include <stdbool.h> 28 #include <errno.h> 29 30 #include "gettext.h" 31 #define _(msgid) gettext (msgid) 32 33 #include "error.h" 34 #include "exitfail.h" 35 #include "quotearg.h" 36 37 #if USE_UNLOCKED_IO 38 # include "unlocked-io.h" 39 #endif 40 41 static const char *file_name; 42 43 /* Set the file name to be reported in the event an error is detected 44 by close_stdout. */ 45 void 46 close_stdout_set_file_name (const char *file) 47 { 48 file_name = file; 49 } 50 51 /* Close standard output, exiting with status 'exit_failure' on failure. 52 If a program writes *anything* to stdout, that program should close 53 stdout and make sure that it succeeds before exiting. Otherwise, 54 suppose that you go to the extreme of checking the return status 55 of every function that does an explicit write to stdout. The last 56 printf can succeed in writing to the internal stream buffer, and yet 57 the fclose(stdout) could still fail (due e.g., to a disk full error) 58 when it tries to write out that buffered data. Thus, you would be 59 left with an incomplete output file and the offending program would 60 exit successfully. Even calling fflush is not always sufficient, 61 since some file systems (NFS and CODA) buffer written/flushed data 62 until an actual close call. 63 64 Besides, it's wasteful to check the return value from every call 65 that writes to stdout -- just let the internal stream state record 66 the failure. That's what the ferror test is checking below. 67 68 It's important to detect such failures and exit nonzero because many 69 tools (most notably `make' and other build-management systems) depend 70 on being able to detect failure in other tools via their exit status. */ 71 72 void 73 close_stdout (void) 74 { 75 bool prev_fail = ferror (stdout); 76 bool none_pending = (0 == __fpending (stdout)); 77 bool fclose_fail = fclose (stdout); 78 79 if (prev_fail || fclose_fail) 80 { 81 int e = fclose_fail ? errno : 0; 82 char const *write_error; 83 84 /* If ferror returned zero, no data remains to be flushed, and we'd 85 otherwise fail with EBADF due to a failed fclose, then assume that 86 it's ok to ignore the fclose failure. That can happen when a 87 program like cp is invoked like this `cp a b >&-' (i.e., with 88 stdout closed) and doesn't generate any output (hence no previous 89 error and nothing to be flushed). */ 90 if (e == EBADF && !prev_fail && none_pending) 91 return; 92 93 write_error = _("write error"); 94 if (file_name) 95 error (exit_failure, e, "%s: %s", quotearg_colon (file_name), 96 write_error); 97 else 98 error (exit_failure, e, "%s", write_error); 99 } 100 } 101